2010-09-30

New Directions in Modern Cosmology, day 4

Highlights for me today were talks by Lewis (Sussex) about lensing in the CMB and Joyce (Paris) about the scale-invariance of gravity and numerical simulations. Lewis showed some beautiful results with WMAP data, in which they can show that the statistics of the CMB are distorted by the slightly anisotropic beam of the satellite combined with the slightly anisotropic scan pattern. This was in the context of lensing, because he finds it using the same techniques that will be used to find lensing-induced distortions to the Planck map.

Joyce showed some beautiful results on gravity, including exceedingly precise simulations of one-dimensional (yes, one-dimensional) gravitational collapse, and analytic description of the behavior of n-body simulations. He is trying to understand whether the departures from scale-invariance seen in n-body simulations (the correlation function is not a power law in the dark sector, while the observed correlation function of galaxies is very close to a power law) could be somehow related to the difference between gravity and the simulations thereof. He doesn't have conclusive results, but his models of the models are impressive.